The rel property of the HTMLLinkElement interface reflects the rel attribute. It is a string containing a space-separated list of link types indicating the relationship between the resource represented by the <link> element and the current document.
The most common use of this attribute is to specify a link to an external style sheet: the property is set to stylesheet, and the href attribute is set to the URL of an external style sheet to format the page.
A string.
const links = document.getElementsByTagName("link");
for (const link of links) {
console.log(link);
}<a> and <area>, HTMLAnchorElement.rel and HTMLAreaElement.rel.HTMLLinkElement.relList